1. Field of the Invention
The present invention relates to an electrical connector, and particularly to a high speed electrical connector having plural circuit board modules.
2. Description of Related Art
With the development of communication and computer technology, high density electrical connectors with conductive elements in a matrix arrangement are desired to construct a large number of signal transmitting paths between two electronic devices. Such high density electrical connectors are  widely used in internal connecting systems of severs, routers and the like requiring high speed data processing and communication.
U.S. Pat. Nos. 6,171,115 and 6,267,604 each disclose a high-speed electrical connector having plural individual circuit boards. The connector comprises a two-piece insulative housing consisting of a front housing portion and an organizer attached to the front housing portion to retain the plural individual circuit boards therebetween. The front housing portion includes a front wall having a plurality of parallel apertures extending therethrough, and upper and lower shrouds extending forwardly from the front wall. Each of the upper and the lower shrouds has plural grooves aligned with respective ones of the apertures. The organizer has a plurality of spaced slots located corresponding to the apertures, and a plurality of openings communicating with the slots in a bottom wall thereof. The circuit boards have mating portions extending through the apertures of the front housing portion for mating with a complementary connector, and mounting edges received in the slots of the organizer. The mounting edges of the circuit boards have a plurality of terminals secured thereon by soldering. The terminals extend through respective openings of the organizer for electrically connecting with a circuit substrate.
However, forming a two-piece insulative housing to hold the circuit board modules is complicated, thus increasing the manufacturing cost. Further, to protect the electrical connector from EMI (Electro Magnetic Interference), an additional EMI shielding member must be provided, which also increases the manufacturing cost.
U.S. Pat. Nos. 5,672,064, 5,702,258 and 5,980,321 disclose an alternative approach to form connectors by using a metal stiffener.
U.S. Pat. No. 5,702,258 discloses a modular electrical connector  comprising a metal stiffener and a plurality of contact modules attached to the metal stiffener. Each contact module includes an insulative housing having a first and a second shroud portions integrally formed therewith to aid in the insertion of a mating connector.
U.S. Pat. No. 5,980,321 discloses a high-speed electrical connector comprises a plurality of wafers side-by-side stacked and a metal stiffener holding the wafers in a required position. Each wafer is made in two pieces, a shield piece and a signal piece. The shield piece is formed by insert molding housing around a front portion thereof. The signal piece is made by insert molding housing around contacts. In order to hold each wafer in the required position without rotation, three connection points are established between the metal stiffener and the wafer. The connection comprises projections formed on the wafer and corresponding slots defined in the stiffener. However, the projections must be accurately aligned with corresponding slots, respectively, thereby increasing the difficulty of assembling the connector. Further, the arrangement of positioning the shield pieces between the adjacent signal pieces reduces the effective signal density.
Hence, an electrical connector having improved metal stiffener is required to overcome the disadvantages of the related art.